Back in 2007, I opted to change the license for my logic textbook, forall x. The removal of the Non-Commercial provision meant that, since then, people have been allowed to sell copies of the book and of any derivative works they might make. At the time, I wrote this:

There is little danger that a publisher will sell an overpriced deluxe edition of forall x, because the Sharealike provision would preclude them from exercising restrictive rights over it. The content would still be free.

I was perhaps a bit too optimistic.

A while later, a company began selling a poorly made ebook version on Amazon. I wrote a review telling people not to buy it and pointing them to where they can download it for free.

Today I discovered that University Press of Florida is offering forall x for $32.50. They assigned it an ISBN and everything. Their product page does not have any product description at all. If you do a search, though, the description includes information about how to get a copy from Lulu where it's available for $8.50.

They also have the title slightly wrong: "Forall x: Introductory Textbook in Formal Logic" rather than "forall x: An introduction to formal logic"